GB856853A - Improvements in or relating to electrical pulse counting apparatus - Google Patents

Abstract

856,853. Electronic counting apparatus. WESTINGHOUSE ELECTRIC CORPORATION. Jan. 16, 1959 [Jan. 17, 1958], No. 1650/59. Class 106 (1). [Also in Group XXXV] A pulse counter comprises a number of bistable stages each comprising two elements and an input pulse sequencing circuit which applies a first input pulse to the odd-numbered stages and the next input pulse to the evennumbered stages, the stages being arranged so that a stage can change from one stable state to the other only when an input pulse is applied to that stage and the preceding stage has already been changed to the second of said stable states. The invention is applied to a system for controlling the temperature of a furnace, Fig. 1. A bimetallic strip varies the output frequency of a generator 12 and a pulse counter 16 counts the number of resultant pulses in a predetermined time. According to how the count compares with a predetermined number so a device 24 controls the supply of fuel to the furnace. Pulse counter, Fig. 2. The pulse counter comprises stages 1-(n), each comprising a pair of NOR elements comprising transistors, the left-hand of which is initially on, i.e. has a more positive output, and the right-hand off. The pulses to be counted are applied to input terminal 70 of a pulse sequence control circuit so arranged that elements 76 and 74 operate to alternate pulses to apply output pulses to the odd- and even-numbered stages 1-(n). The right-hand element of each stage is governed by the left-hand element of the preceding stage. Consequently the first pulse reverses the first stage and so on. The nth pulse reverses the nth stage to bias the first stage again, effect transfer over terminal 89 to the next denomination, and through elements 90, 92, 94 to restore the several stages 1-(n). The several stages may alternatively be restored in cascade manner by a slow-acting pulse applied to terminal 88. A modification of the pulse sequence control circuit is described (Figs. 4 and 5, not shown). Pulse shaper, Fig. 6. An A.C. frequency is applied to a NOR element 114, the output of which is split into a direct path to element 118 and a delay circuit through 120, 122, 128 to the element 118. NOR element 118 produces an output signal only when there is no signal on either of its inputs, so producing a squarewave output dependent only on the values of resistor 124 and capacitor 126 and independent of the A.C. frequency. Count level sensing circuit, Figs. 7, 8. The outputs of the several stages of the counter of Fig. 2 are connected to terminals 15, 17, 19 ... 31, outputs on which have the significance. indicated in Fig. 7. Fig. 8 shows an arrangement whereby when a three-denomination number is exceeded a NOR element 53 has an output. The fuel control device mav be isolated from the counters during count intervals by a circuit described with reference to Fig. 9 (not shown).